Sheet positioner

ABSTRACT

An apparatus particularly suited for the layup of plywood panels operates to position an individual sheet of veneer over an increasing stack of such veneer sheets. The positioning apparatus consists of a flexible sheet metal surface which is actuated by a hydraulic cylinder to impart the proper trajectory to the veneer sheets as they are thrown outwardly from the output edge of the positioner surface.

United States Patent Brookhyser [451 Dec. 5, 1972 I54] SHEET POSITIONER [72] Inventor: Byron B. Brookhysen Milton, Wash.

[73] Assignee: Weyerhaeuser Company, Tacoma,

Wash.

[22] Filed: March 29, 1971 211' Appl.No.: 128,779

[52] U.S. Cl ..271/68, 214/6 D, 271/75 [51] Int. Cl. ..B65h 29/18 [58] Field of Search ..271/68, 69, 71, 63, 75, 8:6,

[56] References Cited UNITED STATES PATENTS Brinson ..271/86 X 2/1931 Johnson .Q ..27l/69X 12/1966 Gibb ..271/63 Primary Examiner--Evon C. Blunk Assistant Examiner-Bruce 1-1. Stoner, Jr. AttorneyPatrick D. Coogan, John M. Crawford, Stuart A. Heller and Bryan C. Ogden [57] ABSTRACT An apparatus particularly suited for the layup of plywood panels operates to position an individual sheet of veneer over an increasing stack of such veneer sheets. The positioning apparatus consists of a flexible sheet metal surface which is actuated by a hydraulic cylinder to impart the proper trajectory to the veneer sheets as they are thrown outwardly from the output edge of the positioner surface.

4 Claims, 3 Drawing Figures r not be further described.

SHEET POSITIONER BACKGROUND OF THE INVENTION This invention relates generally to an apparatus which positions thin sheet material as it comes from a conveyor surface over an increasing stack of such sheet material. More particularly it relates to an apparatus which may be utilized to position wood veneer sheets over an increasing stack of plywood panels.

In the manufacture of plywood panels, it is common to convey and then sequentially stack individual sheets of verythin and flexible wood veneer. Although the present invention will be described in reference to thin wood veneer, it is not necessarily limited to wood but may also be utilized in thestacking of thin plastics, sheet metal, or the like. It is the intent in plywood manufacture to convey the individual veneers to a layup station where the sheets are sequentially stacked in the proper position to form the wellknown multi-ply panels. i

In general construction of plywood panels, the sheet dimension is usually on the order of 4 feet by 8 feet and is comprised of at least a face and back sheet together with a core sheet. The face and back veneer sheets nor mally have their respective grains running parallel'to the longer dimension of the sheet. The core sheet grain thenwill run perpendicular to the grain of the face and back veneer sheets. In panels having five or more plys, a center veneer sheet is utilized which also has its grain running parallel to the longer dimension. The details of plywood formation are well-known in the art and will As plywood manufacture has become more automated over the past several years, various plywood layup machines have attempted to increase the rate at which panels may "be formed. The present invention facilitates the formationof plywood panels in providing a positioning device for each individual veneer sheet at the layup station.

. An example of apositioning device to properly align veneer sheets may be seen by referring to issued US. Pat. No. 3,312,327 in the names of C. C. Clapp et al., which has been assigned to the assignee of the present invention. In this patent a retractable fork table Accordingly, from the foregoing, one object of the present invention is to provide the proper trajectory for a veneer sheet as it leaves a conveyor surface.

Another object is to provide a sheet positioner which I SUMMARY OF THE INVENTION Briefly, this invention is practiced in one form by placing a thin piece of flexible positioner material across the output end of a conveyor surface. The'flexible material extends further along the direction of travel where it terminates and is firmly attached to a supporting member. The supporting member communicates with a hydraulic cylinder and is thusly caused to move upwardly and downwardly thereby flexing the sheet positioning material. As an individual veneer sheet passes over the surface of the flexible material the hydraulic cylinder is actuated and the flexible material flexes downwardly causing the individual veneer sheet to assume its intended trajectory to a position over the layup table. l

BRIEF DESCRIPTION OFTHE DRAWING FIG. 1 is a side elevation view cut away showing a veneer sheet after is has assumed the proper trajectory over the layup table.

FIG. 2 is a perspective view of the present invention showing the relative dimensions of the flexible sheet operates to deposit veneer sheets on a layup table. Only face, centers and backs are positioned by the fork table and it will be appreciated that the grain direction of the face, centers and backs is parallel to the direction of the veneer travel.

When transporting individual face, centers and backs down a conveyor surface toward a layup station with the grain running transverse to the direction of travel, it will be appreciated that as a veneer sheet leaves the end of a conveyor surface, it is likely that the sheet will tend to flex and bend downwardly about the individual grain lines. In order to prevent this natural movement when the supporting function of the conveyor surface is removed, it is necessary to structure the veneer sheets trajectory as it leaves the end of the conveyor surface. Of course, by structuring the veneer sheet trajectory in the desired manner, each sheet will be thrown outwardly by the momentum imparted to it by the conveyor a sufficient amount such that each sheet then drops in a natural manner onto the layup table without dearranging in flight.

DESCRIPTION OFTHE PREFERRED EMBODIMENT Referring now to the drawing, the sheet positioner of the present invention is comprised of a frame consisting of two spaced apart base members indicated as 1 and 2 respectively. The base members 1,2 may be comprised of any suitable structural element but are shown as being comprised of channel sections in the drawing. The base members 1,2 extend upwardly a suitable distance to provide extension members 3 and 4 respectively. The base members 1,2 are, rigidly attached to ground while they extend generally vertically upward to a horizontal transition plane where they become the extension members 3,4. The transitional plane is at generally the same vertical level as is the flexible positioner surface 12.

Since the sheet positioner will be placed in an environment where a conveyor surface will be utilized to impart momentum to the individual veneer sheets one such conveyor surface is generally indicated as 5. In the embodiment shown, conveyor surface 5 is comprised of a plurality of endless flat belts 6, portions of which are shown in FIGS. l3. The conveyor surface 5 is generally in a horizontal plane and is approximately at the same vertical level as is the transition plane where the base members become extension members. The conveyor surface 5 is intermittently powered by a suitasheet as it leaves the output end.

It will be noted that the channel members are spaced apart in order to accommodate the longer dimension of a sheet of veneer. Likewise, the plurality of endless flat belts 6 are spaced so that the veneer sheets are properly supported as momentum is imparted to them.

The endless flat belts 6 are trained around a plurality of individual wheels 7 which are in turn securely attached to a rotatable shaft indicated as 8. A pair of stationary brackets 9 may be attached to the upstream flanges of the channel members to provide the support for rotatable shaft 8.

The terms upstream and downstream will be used in reference to the direction of travel of an individual veneer sheet as it travels along the conveyor surface and then over the sheet positioner. This direction of travel is indicated by the directional arrow in FIG. 1.

Extending laterally between the two channel members and in the same horizontal plane as is the conveyor surface 5 is a transition surface indicated as 10. The transition surface 10 is supported as it traverses the distance between the channel members by a rigid tubular member 11. The transition surface 10 provides the continuation surface for the conveyor'surface 5 as the veneer sheets leave the conveyor but prior to their travel across the flexible positioner surface 12, which is the primary part of the present invention. The transition surface 10 may be of any suitable material such as sheet metal and has a plurality of cut out portions 13 for the accommodation of the endless flat belts 6 with their respective wheels 7. The longexposed upstream edge of the transition surface 10 is bent downwardly such that it is below the top level of the conveyor surface 5 in order to prevent any veneer sheets from being propelled into the edge and thereby causing a malfunction. The transition surface 10 and tubular member 11 may be readily seen by referring to FIGS. 2 and 3.

The flexible positioner surface 12 also extends laterally between the two channel members but is designed to flex about a laterally extending base line 14. The positioner surface 12 is ideally comprised of a thin sheet of strong sheet metal which is easily flexed about flexture lines running parallel to the longer dimension of the positioner surface. Again support for the positioner surface 12 at the fixed base line 14 is provided by the tubular member 11 which is positioned slightly beneath both the positioner surface 12 and transition surface 10. A small spacer block 15 extends upwardly from the tubular member 11 and its upper surface is the actual surface on which the upstream edge of the positioner surface rests. The upstream edge of the positioner surface 12 may be attached to the spacer block 15 in any suitable manner but ideally is attached through the use of removable screws 154 so that the positioner surface 12 may be inspected at regular intervals.

Cut out portions 16 and 17 respectively in the downstream flanges of the channel members are provided for the accommodation of a pair of pivotal arm members 18 and 19. It is through the use of pivotal arm members 18 and 19 that the flexible positioner surface 12 is caused to flex to an upward or downward position as the sequence of operations may require. A pair of pivot mounting brackets 20 and 21 may be securely attached to the tubular member 11 and are adapted to provide the respective pivot points 22, 23 about which the pivotal arm members l8, 19 travel. Extending laterally between the respective pivotal arm members 18, 19 and securely fastened to each is a rigid pipe member 24. It is through rigid pipe member 24 that unity of operation occurs in that both pivotal armmembers 18, 19 are caused to move in a unitary fashion upon actuation from the single hydraulic cylinder25.

Hydraulic cylinder 25 extends ,downwardly from a mountingbracket 26 which is firmly attached to the downstream flange of the extension member 3. The operating ram 27 is pivotally connected to the pivotal arm member 18 at the pivot point 28..

As previously noted, the base line 14 represents the input edge to the flexible positioner surface 12. The output edge of the flexible positioner surface 12 is securely fastened to a laterally extending bar member 29 which is rotatably connected to the downstream ends of the respective pivotal arm members 18, 19. The bar member 29 is adapted to rotate about rotation points 30 and 31 as the hydraulic ram 27 motivates the pivotal arm members 18, 19 upwardly and downwardly. The reason for allowing the bar member 29 to rotate is to allow surface 12 to assume a cross sectional shape approximating a true are about a geometric center 32 located on an imaginary vertical plane 33 through pivot points 22, 23 as seen in FIG. 3.

The hydraulic cylinder 25 is selected in order to allow the ram 27 to turn the arm members 18,19 through a total angle B on the order of 50. With this, the ram will turn the positioner surface output edge through a positive and negative angle of approximately 20 about a horizontal plane through the base line 14.

It will be appreciated that a suitable control system will be provided in order to provide the proper sequencing for the hydraulic cylinder 25.

The layup station is generally indicated as 34 and as would be expected is positioned slightly downstream from the output edge of the flexible positioner surface 12. The layup station 34 is comprised generally of a layup table 35 which may be of the type that is adjustable in the vertical direction such that as the stack 36 builds up it will automatically be lowered to a more convenient position. A back stop 37 is positioned axially from the output edge of the positioner surface 12 a distance that is of a greater dimension than the shorter dimension of a veneer sheet. Back stop 37 extends upwardly from the ground level and reaches a height suitable to retard air escape from under stop each individual veneer sheet as it is thrown clear from the positioner surface 12. Positioned opposite the back stop 37 is a vertically extending alignment surface 38. Alignment surface 38 likewise extends vertically upward from the floor surface and is utilized to provide a straight edge to the forming stack 34 of veneer sheets. In the normal course of operation, two human operators will be stationed on opposite sides of the shorter dimension of the stack of veneer sheets and will guide each veneer sheet from its suspended airborne position to a position atop the stack 34 and to a position where the trailing longer edge of the sheet abuts the alignment edge 38. I

i As individual veneer sheets are continually positioned atop the increasing stack 36 to layup table 35 will automatically lower itself to assume an always convenient height for the proper placement of the veneer sheets.

OPERATION OF THE INVENTION As previously mentioned in the background of the invention, the flexible positioner surface is particularly useful in the positioning of veneervsheets where the grain direction is perpendicular to the direction of sheet travel. The operation of the present invention will be described by following an individual veneer sheet down the conveyor surface 5 over the positioner surface 12 and onto the veneer stack 36.

Assume first that a veneer sheet has been placed on the conveyor surface 5 and is waiting to be conveyed to the veneer stack. At the proper sequential moment the conveyor surface 5 is powered which moves the veneer sheet toward the positioner surface and also gives the veneer sheet a suitable amount of momentum to carry it past the output edge of positioner surface 12 and over the veneer stack 36. At this instant the positioner surface 12 is in its upper position with the hydraulic ram 27 being fully retracted. As the leading edge of the veneer sheet passes over the output edge of the positioner surface 12, the hydraulic ram 27 begins its downward stroke causing the flexible positioner surface 12 to flatten and then flex downward. The up and down positions of surface 12 can be seen by referring to FIG. 3. The timing of the ram stroke is such that the positioner surface 12 is in its down position just as the trailing edge of the veneer sheet passes over the output edge of the positioner surface 12. Just as the veneer sheet clears the positioner surface, the hydraulic ram 27 retracts and the positioner surface returns to its up position in order to receive the next veneer sheet in the normal sequence of operation.

After the veneer sheet has left the positioner surface 12 and at an instant before gravity causes it to float downwardly it assumes the shape and position as depicted in FIG. 2. The bend in the veneer sheet is due to the natural flexibility of the veneer while the curviture of the bend and the position of the sheet is due to the action of the flexible positioner surface 12. With the veneer sheet in the position as indicated and with the curviture as indicated it will then naturally begin to fall toward the top of stack 36. Since the veneer sheets are light in weight and of relatively large surface area, the buoyant effect of the air will cause them to stop travelling axially and fall gently on the stock. At this point it is helpful'although not absolutely necessary to provide two human operators to guide the veneer sheet so that its trailing edge will be positioned against the alignment edge 38. I

While a detailed example of the principal embodiment has been described, it is understood that many changes and modifications may be made in the abovedescribed sheet positioner without departing from the spirit of the invention. All such modifications are in tended to be included within the scope of the appended claims.

What is claimed is:

1. A positioning apparatus for thin sheets, comprismg:

a substantially rigid frame having at least two spaced apart base portions, I a surface, sloping generally upward, having an input side and an output edge with the slope of said surface being in the range of from 0.30 to 0.50,

means to motivate a thin sheet across said surface arranged and adapted to provide sufficient momentum for the thin sheet to be propelled over the surface and past the output edge, means to accept the thin sheets as they leave the output edge, and

means to flex the surface to a downwardly sloping position as a thin sheet is motivated across the surface by said sheet motivating means.

2. The sheet positioner as in claim 1 in which the surface is comprised of flexible sheet metal.

3. The sheet positioner as in claim 1 in which the flexing means is comprised of a sequentially operable activating cylinder arranged and adapted to cause the output edge of the positioner surface to move generally vertically downward while the positioner surface is allowed to flex as a thin sheet passes over said surface.

4. The sheet positioner as in claim 1 in which said sheet accepting means include a stacking table positioned axially from said output edge and a backstop means to halt the axial travel of said sheet. 

1. A positioning apparatus for thin sheets, comprising: a substantially rigid frame having at least two spaced apart base portions, a surface, sloping generally upward, having an input side and an output edge with the slope of said surface being in the range of from 0.30 to 0.50, means to motivate a thin sheet across said surface arranged and adapted to provide sufficient momentum for the thin sheet to be propelled over the surface and past the output edge, means to accept the thin sheets as they leave the output edge, and means to flex the surface to a downwardly sloping position as a thin sheet is motivated across the surface by said sheet motivating means.
 2. The sheet positioner as in claim 1 in which the surface is comprised of flexible sheet metal.
 3. The sheet positioner as in claim 1 in which the flexing means is comprised of a sequentially operable activating cylinder arranged and adapted to cause the output edge of the positioner surface to move generally vertically downward while the positioner surface is allowed to flex as a thin sheet passes over said surface.
 4. The sheet positioner as in claim 1 in which said sheet accepting means include a stacking table positioned axially from said output edge and a backstop means to halt the axial travel of said sheet. 